Objective:
Rangelands represent the largest agroecosystem in the West, sustaining rural economies and providing a suite of essential non-market ecosystem services that globally are valued between US $15 and 54 trillion per year. Non-native invasive plants, however, are spreading across western rangelands almost unimpeded, threating the economic sustainability of ranching enterprises and the critical ecosystem services these working landscapes provide. We recently were asked to lead a major portion of the NRCS Rangeland Conservation Effects Assessment Project (CEAP) examining the effectiveness of rangeland weed management practices and found that while the general philosophy of IPM was well supported among stakeholders, adoption of IPM systems was low. Our broad goal is to build off of this CEAP effort and reduce the gap between the theory and practice of rangeland weed IPM through work in two key areas. The first focuses on understanding on-farm development and application of IPM systems and the social learning dynamics that result in broad regional adoption. The second focuses on quantifying benefits of rangeland IPM for multiple-ecosystem services. We will accomplish goals and supporting objectives using a network of four partner ranches in California and Oregon, examining both the impacts of applying IPM systems as well as the socioeconomic process associated with adoption through peer-learning networks. Closing this gap between the theory and practice of IPM on rangeland likely represents one of the single largest opportunities for advancing IPM adoption in the United States.

Approach:
To compare weed treatment costs and weed treatment impacts between our rangeland weed IPM decision framework and conventional weed management approaches we will select two, 100 acre pastures on each of four ranches. Pastures represent a common ranch-scale management unit (i.e. producers make specific agricultural management decisions at the pasture level). In this ranch-scale study, ranches are blocks and pastures are the experimental unit. Each pasture in each block will be randomly assigned to be managed using our rangeland weed IPM decision framework or managed under current management decision processes.
For pastures enrolled under our IPM decision framework, producers will design an IPM system using our published decision framework to select combinations of prevention tactics and weed management tools and strategies that are compatible with the economical and logistical constraints of the ranching enterprise and support other key management objectives (e.g. herd production, animal performance, drought preparedness). These treatments and strategies may include tactics for preventing weed spread, as well as timing, duration and intensity of grazing, herbicide application, seeding, targeted movement of grazing animals using supplement and temporary fencing, as well as targeted application of IPM treatments in different areas of the pasture. Pastures enrolled in conventional weed management will receive existing weed management practices, which may vary ranch to ranch. Cost of labor, materials and supplies will be tabulated for each pasture treatment and we will measure pre and post-treatment abundance and diversity of desired plant species and as well as weed species composition and abundance. Pre-treatment data will be collected fall of 2013 and treatment data will be collected spring of 2014, 2015 and 2016. Data will be analyzed using mixed-model Analysis of Variance with block and year as random factors in the model (SAS Institute Inc 2008).
We will also evaluate, at a ranch scale, the benefits of rangeland weed IPM decision systems for enhancing multiple ecosystem services compared to conventional weed management approaches. We will use the same experimental pastures as those used in Research Objective 1 and also will add a third 100 ac reference pasture adjacent to each ranch that represents an intact, healthy rangeland agroecosystems. This will allow us to evaluate the degree to which IPM enhances ecosystem services relative to conventional weed management practices and allow us to quantify the degree to which IPM enhances these services relative to a healthy, intact rangeland agroecosystem. We will measure five characteristics that tie to key ecosystem services in these systems including: 1) Livestock carrying capacity 2) fine fuel loads and fuel load continuity 3) soil carbon dynamics 4) nitrogen retention and 5) insect diversity. Effects of pasture management systems (conventional vs. an IPM system for invasive plants) on multiple ecosystem services will assessed by using multivariate linear regression to analyze effects of pasture treatments on our five indicators of key ecosystem services.